Balloon devices and methods for use

ABSTRACT

Balloon catheters and methods are provided for selectively occluding blood flow into a right atrium of a patient&#39;s heart communicating with an inferior vena cava (IVC) and superior vena cava (SVC). In one embodiment, a catheter includes first and second balloons adjacent one another on a distal end of the catheter shaft. During use, the distal end is introduced into the right atrium and positioned such that the first balloon is located within the right atrium. The first balloon is expanded within the right atrium and the catheter shaft directed such that the expanded first balloon engages at least a portion of the IVC to prevent substantial inflow into the right atrium from the IVC. The second balloon is then expanded to limit inflow into the right atrium from the SVC, and a medical procedure is performed within the patient&#39;s body.

RELATED APPLICATION DATA

The present application claims benefit of provisional application Ser.No. 62/272,002, filed Dec. 28, 2015, the entire disclosure of which isexpressly incorporated by reference herein.

FIELD OF THE INVENTION

The present application relates to balloon devices and methods for usingthem, and, more particularly, to a double lumen balloon catheter forinflow-occlusion of the inferior and superior vena cava and a method ofcombining IVC and SVC occlusion for cardiac output reduction.

BACKGROUND

Balloon occlusion in or on top of the inferior vena cava (IVC) is usedtoday to reduce the venous return to the right heart in order todecrease cardiac output during deployment of stent-grafts in thethoracic aorta (TEVAR). This technique is used to reduce the systolicjet of the left ventricle that may displace the graft when partiallyopened. Thereby, IVC-occlusion improves accurate and precise deploymentof stent-grafts. The sudden increase in resistance in the aorta when astent-graft is opened may also harm the left-ventricular function. Thisissue is also improved when the reduction of venous return reducescardiac output by balloon inflation in or on top of the IVC. In TEVAR,the cardiac output reduction achieved by IVC balloon occlusion issufficient and easily practiced.

Competing techniques of cardiac output reduction during TEVAR includemedically induced temporary cardiac arrest by adenosine and rapidventricular pacing (“RVP”). RVP is a well-established technique toreduce cardiac output during TEVAR, but carries some significant risksand drawbacks.

The drawbacks of RVP include the short period of time during which RVPis tolerated, so deployment needs to be quick, a cardiologist isfrequently needed during the procedure, and there are individualdifferences in compliance. The risks include that the heart may notreturn to normal rhythm and consequently require CPR and, that the heartventricles may fill during the RVP due to the continued venous returnand thereby expand the ventricle, which may not handle this high volume.The latter may lead to the need for manual cardiac massage to pump outthe left ventricular volume. Overall, this problem decreases theapplicability of RVP in hearts with decreased pump-function.

Another field where cardiac output reduction is routinely practiced isin trans-catheter aortic valve implantation (TAVI). Here, RVP is used bymost cardiologists and cardiac surgeons. In TAVI, the shortcomings ofRVP are more frequent than in TEVAR as patients more frequently have alimited left ventricular myocardial function due to structural andcoronary heart disease. Most operators find IVC-balloon occlusion inTAVI not applicable, as it does not completely stop cardiac output dueto the continued venous return from the superior vena cava (SVC) and thecoronary sinus.

A simultaneous balloon-occlusion of the IVC and the SVC would almostcompletely stop the venous return to the heart and thereby fast andeffectively reduce the cardiac output to near zero. Only venous returnfrom the coronary sinus would be left. In contrast to RVP, thistechnique will not lead to ventricular expansion and therefore reducethe harmful side-effects of cardiac output reduction by RVP.

This maneuver of simultaneously stopping the IVC and SVC return isroutinely used in open cardiac surgery, for instance when a sideanastomosis of the ascending aorta is opened, to allow slow andcontrolled filling and reduce strain on the new anastomosis. However,such procedures are not generally used during minimally-invasiveprocedures.

SUMMARY

The present invention is directed to balloon devices and methods forusing them, and, more particularly, to a double-balloon catheter and amethod of controlled occlusion of the IVC and the SVC in order to reducevenous return and cardiac output. The devices and methods herein may beused during a variety of medical procedures, particularly during TAVI,TEVAR, and other interventions and operations that may require cardiacoutput reduction. The devices and methods herein may provide one or moreadvantages compared to conventional RVP (the most common method usedtoday), such as ease of use, reliability, gentleness, and lowercomplication rate of CPR and cardiac massage.

In accordance with one embodiment, a balloon catheter is provided forselectively occluding blood flow into a right atrium of a heartcommunicating with an inferior vena cava (IVC) and superior vena cava(SVC) that includes an elongate shaft comprising a proximal end and adistal end sized for introduction into a patient's body. A first balloonis carried on the distal end formed from compliant or semi-compliantmaterial and having a first length, and a second balloon is carried onthe distal end adjacent the first balloon formed from semi-compliant ornon-compliant material and having a second length longer than the firstlength. The first and second balloons are independently expandable,e.g., such that the first balloon may be expanded and engaged with theIVC to prevent substantial inflow from the IVC into the right atrium,and the second balloon may be expanded thereafter to limit inflow fromthe SVC into the right atrium.

In accordance with another embodiment, a method is provided forselectively occluding blood flow into a right atrium of a patient'sheart communicating with an inferior vena cava (IVC) and superior venacava. A distal end of a catheter shaft may be introduced into thepatient's vasculature, the distal end carrying first and second balloonsin collapsed conditions, the first balloon formed from compliant orsemi-compliant material and having a first length, the second ballooncarried on the distal end adjacent the first balloon formed fromsemi-compliant or non-compliant material and having a second lengthlonger than the first length. The distal end may be advanced into theright atrium, and positioned such that the first balloon is locatedwithin the right atrium. The first balloon may be expanded within theright atrium, and the catheter shaft may be directed such that theexpanded first balloon engages at least a portion of the IVC to preventsubstantial inflow into the right atrium from the IVC. The secondballoon may then be expanded such that the second balloon engages atleast a portion of the SVC to limit inflow into the right atrium fromthe SVC, and a medical procedure may be performed within the patient'sbody.

In accordance with still another embodiment, a balloon catheter isprovided for selectively occluding blood flow into a right atrium of aheart communicating with an inferior vena cava (IVC) and superior venacava that includes an elongate shaft comprising a proximal end, a distalend sized for introduction into a patient's body, and an inflation lumenextending between the first and second ends; and a balloon carried onthe distal end comprising a first region having a first length and asecond balloon adjacent the first region having a second length longerthan the first length, the balloon formed from material such that thesecond region expands to a preset expanded diameter and the first regionexpands to a diameter larger than the present expanded diameter.

Other aspects and features of the present invention will become apparentfrom consideration of the following description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is best understood from the following detaileddescription when read in conjunction with the accompanying drawings. Itwill be appreciated that the exemplary devices shown in the drawings arenot necessarily drawn to scale, with emphasis instead being placed onillustrating the various aspects and features of the illustratedembodiments.

FIG. 1A is a side view of an exemplary embodiment of a double ballooncatheter.

FIG. 1B is a cross-section of the catheter of FIG. 1A taken at 1B-1B.

FIGS. 2-6 are cross-sectional views of a patient's body showing anexemplary method for using a catheter, such as the catheter of FIG. 1A,to perform a procedure, e.g., within the right atrium and the vena cava.

FIGS. 7A-7C are cross-sectional views of a patient's body showing anexemplary method for using a catheter including a single elongateballoon to selectively isolate the superior and inferior vena cava fromthe right atrium.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Turning to the drawings, FIGS. 1A and 1B show an exemplary embodiment ofa catheter 8 including a shaft or tubular body 10 including a first orproximal end 12, a second or distal end 14 sized for introduction into apatient's body (not shown), a handle or hub 50 on the proximal end 12,and one or more balloons 20 carried on the distal end 14. For example,as shown in FIG. 1A, first and second balloons 20 a, 20 b may beprovided adjacent one another on the distal end 14 of the shaft 10,e.g., with the first or proximal balloon 20 a having a first length thatis shorter than a second length of the second or distal balloon 20 b.

In addition, the shaft 10 includes one or more lumens 16 extending atleast partially between the proximal and distal ends 12, 14. Forexample, a central or instrument lumen 16 a may extend from a first port52 a in the hub 50 through the shaft 10 to a distal or outlet port 17,which may be sized to receive one or more instruments, e.g., a guidewireor other rail (not shown). Optionally, the first port 52 a may includeone or more seals, e.g., a hemostatic valve (also not shown), which mayprovide a substantially fluid-tight seal, while accommodating insertionof one or more instruments or fluids into the instrument lumen 16 a.Optionally, a side port (not shown) may be provided on the hub 50 thatcommunicates with the instrument lumen 16 a, e.g., for delivering fluidinto and/or aspirating fluid from the instrument lumen 16 a, e.g.,around an instrument inserted into the instrument lumen 16 a. In yetanother option, the instrument lumen 16 a may include lubriciousmaterial or may include one or more coatings on the inner surfacethereof having desired properties, e.g., a lubricious coating, to reducefriction and/or otherwise facilitate introducing an instrument throughthe instrument lumen 16 a.

In addition, the shaft 10 may include one or more inflation lumenscommunicating with the interiors of the balloons 20, e.g., a firstinflation lumen 16 b communicating between a second port 52 b on the hub50 and the interior of the first balloon 20 a and a second inflationlumen 16 c communicating between a third port 52 c on the hub 50 and theinterior of the second balloon 20 b. As shown in FIG. 1B, the inflationlumens 16 b, 16 c may be provided opposite one another around theinstrument lumen 16 a. Alternatively, the lumens 16 may be provided inother configurations or positions, which may remain the same or may varyalong the length of the shaft 10, as desired. Generally, the instrumentlumen 16 a will be larger than the inflation lumens 16 b, 16 c, e.g.,sized to accommodate a 0.0035 inch guidewire.

As shown in FIG. 1A, the second and third ports 52 b, 52 c may includeone or more connectors 54 b, 54 c, e.g., a male or female Luer fitting,a stop-cock, and the like, which may allow a source of inflation mediaand/or aspiration (also not shown) to be coupled to the ports 52 b, 52 cand/may selectively allow access and/or isolate the inflation lumens 20b, 20 c. For example, a syringe carrying saline or other fluid (notshown) may be coupled to each of the ports 52 b, 52 c (e.g., twosyringes simultaneously, or one syringe separately) such that a plungerof the syringe may be selectively advanced to direct fluid through thecorresponding inflation lumen 16 b, 16 c to inflate the correspondingballoon 20 a, 20 b, and/or may be withdrawn to remove the fluid fromwithin the corresponding balloon 20 a, 20 b to deflate the balloon 20 a,20 b. Thus, in this embodiment, the balloons 20 a, 20 b may beexpandable independently of one another, e.g., as described furtherelsewhere herein.

The shaft 10 may have a length sufficient to extend from a locationoutside a patient's body, e.g., a percutaneous entry site, into thepatient's vasculature, e.g., such that the distal end 14 may beintroduced into or adjacent a heart 90 (not shown, see, e.g., FIGS.2-6), as described elsewhere herein. An exemplary length of the shaft 10may be at least about eighty centimeters (80 cm), e.g., sufficientlylong to allow introduction from the femoral veins into the vena cava 92,96 (not shown, see, e.g., FIGS. 2-6).

The shaft 10 may have a substantially uniform construction and sizealong its length between the proximal and distal ends 12, 14.Alternatively, the mechanical properties and/or geometry of the shaft 10may vary along its length. For example, a distal end 14 of the shaft 10may be substantially flexible to facilitate advancement through tortuousanatomy, while the proximal end 12 may be semi-rigid or rigid to enhancepushability and/or torqueability of the shaft 10 without substantialrisk of buckling or kinking. Optionally, a distal portion of the shaft10 underlying the balloons 20 a, 20 b may have variable constructionalong its length, e.g., being more rigid beneath and/or between theballoons 20 a, 20 b to maintain balloon spacing and/or otherwisefacilitate manipulation of the catheter 8 in a desired manner.

With continued reference to FIG. 1A, the first balloon 20 a may have alength that is shorter than the second balloon 20 b. In an exemplaryembodiment, the first balloon 20 a may be formed from compliant and/orelastic material, e.g., such that the size of the first balloon 20 a mayvary proportionally to the volume of fluid introduced into its interiorand/or to facilitate the first balloon 20 a changing shape, e.g., toconform to surrounding anatomy, as described further below. In anexemplary embodiment, the first balloon 20 a may expand to a diameter ofat least about fifty millimeters (50 mm) and may have a length of notmore than about four centimeters (4 cm).

In contrast, the second balloon 20 b may be relatively long compared tothe first balloon 20 a, e.g., sized to inflate to a diameter betweenabout twenty to forty millimeters (20-40 mm) and having a length betweenabout eight and fifteen centimeters (8-15 cm). The second balloon 20 bmay be formed from compliant or semi-compliant material, e.g., which maylimit the size of the second balloon 20 b and/or allow some conformanceto surrounding anatomy. Generally, the second balloon 20 b is configuredto be inflated after inflating the first balloon 20 a, e.g., such thatat least a portion of the second balloon 20 b sits on or otherwiseoverlies, abuts, or contacts at least a portion of the inflated firstballoon 20 a, as described further elsewhere herein. Optionally, thematerial of the shaft 10 may be relatively stiffer in the area of theballoons 20 a, 20 b than other sections of the shaft 10, e.g., toprevent proximal migration of the second balloon 20 b, e.g., towards orunder the proximal balloon 20 a.

In an alternative embodiment, instead of a single balloon for the secondor distal balloon 20 b, a pair of concentric balloons (not shown) may beprovided, e.g., with inner and outer balloons having lengths similar tothat shown for the second balloon 20 b. The inner and outer balloons maycommunicate with separate inflation lumens (also not shown) such thatthe inner and outer balloons may be expanded independently of oneanother. For example, the outer balloon may be formed from compliant orsemi-compliant material while the inner balloon may be formed fromnoncompliant material. In this manner, the inner balloon may be inflatedinitially, which may cause the inner balloon to be expanded to a presetexpanded diameter and/or shape given its noncompliant material and theouter balloon may be inflated thereafter to expand outwardly from theexpanded diameter of the inner balloon, which may enhance engagementand/or sealing, as described elsewhere herein.

Optionally, as shown in FIG. 1A, the shaft 10 and/or the balloons 20 a,20 b may include one or more markers 30, e.g., bands of radiopaquematerial, cinched, deposited, secured, or otherwise applied around theshaft 10 at desired locations, e.g., to facilitate identifying theproximal and distal ends of the balloons 20 a, 20 b using externalimaging, such as fluoroscopy. In the exemplary embodiment shown, a firstmarker 30 a may be provided at the proximal end of the first balloon 20a, a second marker 30 b may be provided between the balloons 20 a, 20 b,and a third marker 30 c may be provided at the distal end of the secondballoon 20 b.

Turning to FIGS. 2-6, an exemplary method for using the catheter 8 ofFIG. 1A is shown, e.g., to isolate the inferior vena cava (“IVC”) 92and/or superior vena cava 96 (“SVC”) communicating with the right atrium94 of a patient's heart 90. Initially, the vasculature of the patientmay be accessed, e.g., after puncture of the femoral vein or otheraccess site within the venous system, and a guidewire 98 may beintroduced into the patient's vasculature, e.g., through the iliacveins, the IVC 92, the right atrium 94, and into the SVC 96. Optionally,a tip of the guidewire 98 may be advanced further, e.g., into thejugular vein as shown in FIG. 2.

Once the guidewire 98 is properly positioned, the distal end 14 of theshaft 10 (with the balloons 20 a, 20 b in collapsed conditions) may beadvanced over the guidewire 98, e.g., alone or in combination with anaccess sheath (not shown). For example, the distal end 14 may beadvanced over the guidewire 98 through the IVC 92 into the right atrium94 such that the first balloon 20 a is advanced and positioned withinthe right atrium 94, e.g., as shown in FIG. 3.

The first balloon 20 a may then be inflated, e.g., via a source offluid, such as a syringe (not shown) coupled to the second port 52 b. Inan exemplary embodiment, the first balloon 20 a may be configured tofully expand upon receiving between about thirty and fifty milliliters(30-50 ml) of saline within its interior, thereby expanding the firstballoon 20 a to an expanded condition, e.g., to a diameter of aboutforty millimeters (40 mm). With the first balloon 20 a exposed withinthe right atrium 94, the first balloon 20 a may expand to asubstantially spherical shape given its compliance, e.g., as shown inFIG. 4.

The catheter 8 may then be partially withdrawn, e.g., to pull theexpanded first balloon 20 a proximally until it engages and/or isreceived at least partially within the IVC 12, as shown in FIG. 5. Asshown, the first balloon 20 a may conform to the outlet of the IVC 92and/or otherwise deform elastically to provide a substantiallyfluid-tight seal, thereby occluding inflow of the IVC 92 into the rightatrium 94, e.g., at the level of the diaphragm. Proximal tension may bemaintained on the shaft 10, e.g., manually or using an external deviceengaging the hub 50 of the catheter 8 (not shown), to maintain the seal.

Turning to FIG. 6, the distal balloon 20 b may then be inflated, e.g.,via a source of fluid, such as a syringe (not shown) coupled to thethird port 52 c. Given its length, the second balloon 20 b may expand toat least partially occlude the SVC 94, e.g., to an extent that providesthe desired cardiac output reduction.

Alternatively, as described above, instead of a single balloon for thedistal balloon 20 b, a pair of concentric distal balloons (not shown)may be provided, e.g., having a length similar to the distal balloon 20b. For example, the outer balloon may be formed from compliant orsemi-compliant material while the inner balloon may be formed fromnoncompliant material. Consequently, instead of a single expansion ofthe distal balloon 20 b, the inner distal balloon may be inflatedinitially, which may cause the inner balloon to be expanded to a presetexpanded diameter and/or shape given its noncompliant material. Forexample, the expanded diameter may be selected to correspond generallyto the diameter of the SVC 96, e.g., to at least partially occlude theSVC 96 when expanded. For example, the inner balloon may slow but notcompletely stop inflow into the right atrium 94 from the SVC 96.

Thereafter, the outer distal balloon may be inflated, e.g., to expandoutwardly from the expanded diameter of the inner balloon. Given thecompliant or semi-compliant nature of the outer balloon, the outerballoon may conform the surrounding anatomy and/or enhance engagement,e.g., with the SVC 96, to enhance occlusion of the SVC 96. Thus, theouter balloon may be selectively expanded and/or collapsed with theinner balloon expanded, as desired, to controllably obstruct inflow fromthe SVC 96.

When a desired pressure curve is achieved, e.g., without a systolic jet,one or more procedures may be performed within the patient's heart,vasculature, and/or other locations within the patient's body. Forexample, as explained above, a TAVI or TEVAR procedure may then beundertaken with the IVC 92 and SVC 96 substantially sealed, e.g., toprevent fluid accumulation within chambers of the heart 90 and/or inother tissues. After the procedure is completed, the second balloon 20 bmay be deflated first and then the tension may be released from thefirst balloon 20 a. The first balloon 20 a may then be deflated and thecatheter 8 and guidewire 98 removed from the patient's body usingconventional methods.

Alternatively, as shown in FIGS. 7A-7C, a catheter 108 may be used thatincludes a single balloon having different regions for selectivelyoccluding the IVC 92 and/or SVC 96. Generally, the catheter 108 includesa shaft 110 including a first or proximal end (not shown), a second ordistal end 114 sized for introduction into a patient's body, similar tothe previous embodiment. However, instead of two balloons, the distalend 114 of the shaft 110 carries only a single relatively long balloon120 having different regions, e.g., a first or proximal region 122 and asecond or distal region 124 that correspond generally to the proximaland distal balloons 20 a, 20 b of the previous embodiment. For example,the proximal region 122 may be relatively shorter than the distal region124. In addition, or alternatively, the balloon 122 may be constructedfrom material such that the proximal region 122 expands to a largerdiameter and/or other cross-section than the distal region 124.

For example, the thickness of the balloon 120 may be varied between theproximal and distal regions 122, 124, e.g., with the wall of the distalregion 124 being thicker than the wall of the proximal region 122. Inaddition or alternatively, the distal region 124 may be formed from arelatively higher Durometer material than the proximal region 122.Further, in addition or alternatively, the wall of the balloon 120 maybe reinforced more along the distal region 124 than the proximal region122 to allow the proximal region 122 to expand greater than the distalregion 124.

In addition, the shaft 110 includes one or more lumens, e.g., aninstrument lumen (not shown) extending between a port in a handle or hub(not shown) and an opening 117 in the distal end 114, e.g., sized forreceiving a guidewire 98 therethrough, similar to the previousembodiment. In addition, the shaft 110 may include an inflation lumencommunicating with an interior of the balloon 120. Thus, in thisalternative, both regions 122, 124 of the balloon 120 may expandsubstantially simultaneously as the balloon 120 is inflated.

Turning to FIG. 7A, during use, with the balloon 120 collapsed, thedistal end 114 of the catheter 108 may be introduced into the patient'sbody, e.g., over a guidewire 98 previously placed to extend from apercutaneous entry site into the patient's heart 90, e.g., through theIVC 92 and right atrium 94 into the SVC 96, as described previously. Forexample, the guidewire 98 may be back-loaded through the opening 117into the instrument lumen, and the shaft 110 may be advanced over theguidewire 98 until the balloon 120 is positioned within the heart 90,e.g., with the proximal region 122 adjacent the IVC 92 and the distalregion 124 extending through the right atrium 94 into the SVC 96.

As shown in FIGS. 7B and 7C, the balloon 120 may be inflated and theshaft 110 manipulated, as needed, to isolate the IVC 92 and/or SVC 96,similar to the previous embodiments. Unlike the previous embodiment,since a single balloon is provided, both regions 122, 124 may expandsubstantially simultaneously. Alternatively, if the distal region 124 isconstructed to resist expansion more than the proximal region 122,during inflation, the proximal region 122 may inflate first to allow theIVC 92 to be selectively occluded before fully expanding the balloon 120and the distal region 124. Once the IVC 92 and SVC 96 are sufficientlysealed, one or more procedures may be performed, similar to the methodsdescribed above.

It will be appreciated that the devices and methods described herein maybe used in minimally-invasive, e.g., catheter-based procedures, as wellas open surgical procedures.

Optionally, the orientation of the balloons 20 a, 20 b and/or regions122, 124 may be reversed on the shaft 10, 110, if desired. For example,if groin access, jugular access, or other similar access sites are used,the configuration of the proximal and distal balloons would be reversedto allow the IVC 92 to be selectively isolated first before at leastpartially sealing the SVC 96.

In yet another option, the shaft may include one or more additionallumens and/or may carry one or more additional balloons (not shown)communicating with the respective lumens, e.g., to provide additionalfunctionality to the catheter.

In still another option, an inner channel may be provided on the shaftthat may be opened and closed from outside the patient's body. This mayallow inflation of both balloons and occluding IVC and SVC first (longermaneuver) and then more accurately occlude or open venous return by thehandle.

It will be appreciated that elements or components shown with anyembodiment herein are merely exemplary for the specific embodiment andmay be used on or in combination with other embodiments disclosedherein.

While the invention is susceptible to various modifications, andalternative forms, specific examples thereof have been shown in thedrawings and are herein described in detail. It should be understood,however, that the invention is not to be limited to the particular formsor methods disclosed, but to the contrary, the invention is to cover allmodifications, equivalents and alternatives falling within the scope ofthe appended claims.

I claim:
 1. A method for selectively occluding blood flow into a rightatrium of a patient's heart communicating with an inferior vena cava(IVC) and superior vena cava (SVC), comprising: introducing a distal endof a catheter shaft into the patient's vasculature, the distal endcarrying first and second balloons in collapsed conditions, the firstand second balloons mounted on the distal end of the catheter shaftadjacent one another, the first balloon formed from compliant orsemi-compliant material and having a first length, the second balloonformed from semi-compliant or non-compliant material and having a secondlength longer than the first length; advancing the distal end into theright atrium; positioning the distal end such that the first balloon islocated within the right atrium; expanding the first balloon within theright atrium; directing the catheter shaft such that the expanded firstballoon engages at least a portion of the IVC to prevent substantialinflow into the right atrium from the IVC; thereafter expanding thesecond balloon such that the second balloon engages at least a portionof the SVC to limit inflow into the right atrium from the SVC; andperforming a medical procedure within the patient's body.
 2. The methodof claim 1, wherein the distal end of the catheter shaft is advancedinto the right atrium from the IVC such that the second balloon at leastpartially enters the SVC.
 3. The method of claim 1, wherein, whendirecting the catheter shaft such that the expanded first balloonengages at least a portion of the IVC, at least a portion of the secondballoon remains within the SVC.
 4. The method of claim 1, wherein thefirst balloon expands to a substantially spherical shape when expandedwithin the right atrium, and wherein the first balloon at leastpartially enters the IVC when the catheter shaft is withdrawn such thatthe first balloon is deformed from the substantially spherical shape toenhance sealing of the IVC.
 5. The method of claim 1, furthercomprising, upon completing the medical procedure: deflating the firstand second balloons back to the collapsed conditions; and removing thecatheter shaft from the patient's body.
 6. The method of claim 1,wherein the second balloon is expanded for sufficient time to reducecardiac output in a desired manner.
 7. The method of claim 1, furthercomprising monitoring pressure within the patient's heart to achieve adesired pressure curve before performing the medical procedure.
 8. Themethod of claim 7, further comprising selectively deflating andinflating the second balloon during the medical procedure to modifyinflow into the right atrium from the SVC to achieve the desiredpressure curve.
 9. The method of claim 1, wherein the medical procedurecomprises implantation of a trans-catheter aortic valve.
 10. The methodof claim 1, wherein the medical procedure comprises deploying astent-graft within the patient's thoracic aorta.
 11. The method of claim1, wherein a marker is provided on the distal end of the catheter shaftbetween the first and second balloons, the method further comprisingusing external imaging to identify the marker and thereby facilitateidentifying the first and second balloons.
 12. The method of claim 1,wherein the first and second balloons each includes a proximal end and adistal end, and wherein the catheter shaft comprises a first markeradjacent the proximal end of the first balloon, a second marker betweenthe distal end of the first balloon and the proximal end of the secondballoon, and a third marker adjacent the distal end of the secondballoon, the method further comprising using external imaging toidentify the first, second, and third markers and thereby facilitateidentifying the first and second balloons.
 13. The method of claim 12,wherein the first marker is used to identify the proximal end of thefirst balloon, the second marker is used to identify the proximal end ofthe second balloon, and the third marker is used to identify the distalend of the second balloon.
 14. The method of claim 1, furthercomprising, after engaging the first balloon to at least a portion ofthe IVC, maintaining proximal tension on the catheter shaft to maintainthe seal and prevent inflow into the right atrium from the IVC.
 15. Themethod of claim 14, further comprising removing the proximal tensionafter completing the medical procedure.
 16. The method of claim 1,wherein the second balloon is expanded to engage the SVC to preventinflow into the right atrium from the SVC until a desired pressure curveis achieved, whereupon the medical procedure is performed.
 17. Themethod of claim 1, wherein the second balloon is formed fromnoncompliant material such that expanding the second balloon slows butdoes not completely stop inflow into the right atrium from the SVC, themethod further comprising expanding a third balloon surrounding thesecond balloon and formed from compliant or semi-compliant material, thethird balloon conforming to surrounding anatomy to enhance occlusion ofthe SVC.
 18. The method of claim 17, wherein the third balloon isselectively expanded and collapsed with the second balloon expanded tocontrollably obstruct inflow from the SVC during the medical procedure.19. The method of claim 1, wherein the second balloon is expanded suchthat it overlies, abuts, or contacts a portion of the first balloon. 20.The method of claim 1, wherein the second balloon is selectivelyexpanded and collapsed with the first balloon expanded to controllablyobstruct inflow from the SVC during the medical procedure.